The invention is related to improving the defrost assembly of an evaporator which is provided in a cooling air channel that is formed at the intermediate wall between the freezing compartment and the refrigerating compartment, and more particularly to improving a defrost assembly which increases the efficiency of the cooling air through the channel, which achieves an even and complete defrost over the evaporator, and prevents excessive heating of the cord heater and heat deformity of the components of the refrigerator.
Referring to FIG. 4, a body 1 of a conventional refrigerator comprises a freezing compartment 5 and a refrigerating compartment 6 which are divided by a top partition 2 and a bottom partition 3. Between the top partition 2 and the bottom partition 3 an evaporating channel 7 is provided, in which an evaporator 8 is placed for heat-exchanging the air fed through from the refrigerated spaces 5,6. Cooling air generated from the evaporator 8 is fed into an exiting passage 10 and is diverted into the freezing compartment 5 and the refrigerating compartment 6 by a fan 9. With this system, a food product to be frozen is stored in the freezing compartment 5 while a food product to be kept in a higher temperature is stocked in the refrigerating compartment 6. By this means, in the structural refrigerator the relatively cool refrigerant passing through the evaporator 8 absorbs heat from the relatively hot moist air coming from the refrigerated spaces 5,6. The difference in temperature between the refrigerant and the air causes ice to be formed on the evaporator 8. To melt the ice, the conventional defrost assembly uses heat tubes 81,81 embedded respectively on the top and bottom portion of a plurality of fins 84 as seen in FIGS. 5 and 6, to which the power is periodically supplied in order to allow the iced evaporator 8 to melt. That is, the evaporator 8 comprises a bracket 82 mounted in the direction of the cooling air, a refrigerant tube 83 which is connected with brackets 82,82 in a plurality of loops, a plurality of fins 84 juxtaposed between the brackets 82,82 which are secured to the tube 83 for widening the heat-exchanging surface, and the heat tube 81 embedded respectively throughout the top and bottom portions of the fin 84 and that of the bracket 82 for melting away the ice on the evaporator 8. On the bottom surface of the evaporating channel 7 the heater cord 31 is provided to prevent the defrost water, which is dropped from the evaporator 8 as the heat tube 83 works, from refreezing. However, because the conventional defrost assembly utilizes the heat tube 81 placed on both sides of the evaporator 8, the volume of the evaporator 8 increases. In order to make the complicated element, many manufacturing process are required. With the line contact between the heat tube 81 to the bracket 82 and the fin 84, an even defrosting of the evaporator 8 is difficult to achieve. Even if the respective gaps in the juxtaposition of the fins 84 are to be relatively narrow in order to receive a more even frost free state from the ice on the evaporator, icing on the fins interrupts the cold air flow through the evaporator, resulting in the inefficiency of the refrigerator. Further, on the downward side of the rear portion of the evaporator the drain channel 85 is provided for the drain water of the evaporator. Due to the drain channel 85 the cold air fed into the front portion of the evaporator does not flow via the terminated portion of the evaporator, thereby resulting in the lower efficiency of the refrigeration. However, the problem described below occurs to the defrost assembly which solves the problem described above. As the temperature of the heating plate, located under the bottom surface of the evaporator, increases, the excessive heat of the heating plate is conducted to the foam insulating material of the intermediate partition and deforms the insulating material which has a relative low heat-resistance. Furthermore, if more insulating material is used to improve the heat-resistance, a problem occurs in that the available volume in the food storage space of the refrigerator is reduced. Additionally, if the heating plate is positioned under the bottom surface of the evaporator and the bimetal and the temperature fuse are positioned between the refrigerant tubes of the evaporator, another problem described below arises. The bimetal serves as the means to prevent the heat plate from receiving excessive heat by cutting the electricity to the heat plate by detecting the temperature of the evaporator. However, when the temperature fuse accompanying the bimetal starts the operation due to the fact that the bimetal is out-of-order, the temperature of the heat plate reaches a higher temperature. This increase in temperature creates a problem because the insulating material under the heat plate becomes deformed and the likelihood of a fire increases. Even when the excessive heat of the heat plate can be prevented when the operating temperature of the fuse is reduced, another problem is that the fuse sometimes erroneously cuts off occasionally where the surrounding temperature is high, as in summer.